An organic electronic device such as, for example, an organic light emitting diode (“OLED”) display, an OLED light source for area illumination, an organic light sensor array, an organic transistor array, or an organic solar cell array require protection from oxygen and moisture in the atmosphere, and therefore employ some form of encapsulation. One common procedure to encapsulate the organic electronic device is to sandwich it between a substrate and an encapsulation cover, and an adhesive around the perimeter of the device holds together the substrate and the encapsulation cover such that there is a continuous perimeter seal around the device.
Typically, the substrate and the encapsulation cover are sealed together using UV-curable adhesive or thermal-cure adhesive. In many cases, use of the thermal-cure adhesive would be advantageous. Thermal-cure adhesive provides many advantages such as good performance and predictable results due to the maturity of the technology. The thermal-cure adhesive needs to be heated to a high temperature in order to cure it. Because of the thickness of the substrate and/or the encapsulation cover (e.g., the thickness can vary from tens of microns to over one millimeter), the substrate and/or the encapsulation cover can be efficient absorbers of the infrared (“IR”) radiation supplied to cure the thermal-cure adhesive and therefore a substantial part of the IR radiation supplied to cure the thermal-cure adhesive can be absorbed by these components thus these components are exposed to high temperatures. The absorption of the supplied IR radiation can damage, for example, the organic active layers of the electronic device, the substrate, and/or the encapsulation cover. In the case of the substrate and/or the encapsulation cover, the heating to the high temperatures can cause these components to become warped.
For the foregoing reasons, there exists a need to encapsulate the organic electronic device using thermal-cure adhesive without damaging components of the encapsulated device such as the organic active layers, the substrate, and/or the encapsulation cover.